Service providers in general and mobile network operators (MNOs) in particular provide a range of communications' services to corresponding subscribers. Such services include, for example, voice, voice over Internet Protocol (IP), voice over long term evolution (LTE), streaming, broadcasting, multicasting, or other services. In providing such services, service providers typically implement different functionalities, e.g., billing functionalities, quality of service (QoS) functionalities, etc., to manage the offered services and the corresponding usage by subscribers.
In order to expand geographical coverage of offered services beyond the network coverage of each service provider, service providers typically engage in interworking and roaming arrangements. When a mobile subscriber is roaming on a visited mobile network and places an outgoing voice call, the voice call is typically handled by the visited mobile network using a voice termination service or network. The mobile subscriber is usually billed at a per minute rate (e.g., $1 per minute) for roaming calls and the billing rate is usually fixed, predetermined by the home network operator, and specific to the region or country the visited mobile network is located. In many cases the calling rate for placing outgoing calls while roaming is very expensive, and is frequently the cause of “bill shock” when mobile subscribers receive their monthly mobile phone bill.